The purpose of the study is to determine the safety of DMP 543 during multiple dosing in patients with Alzheimer's disease. Identification of a minimum intolerable dose as defined by adverse experiences will be subject to the limitation of individual peak plasma concentrations, not to exceed 5.0 ng/ml during dosing. The study will be a single-site, placebo-controlled escalating multiple dose, inpatient and outpatient study. Yale will be the only study site. Study was terminated in November 1998 by Industry Sponsor.